Method for the prevention of corrosion



Patented Sept. 21, 1943 UNITED STATES PATENT OFFICE METHOD FOR THE PREVENTION OF CORROSION 7 Peter Heidt, Philadelphia, Pa., assignor to Meyer A. Mathiasen, Philadelphi aPa.

No Drawing. Application September 5, 1940,

Serial N0. 355,521

8 Claims.

. carry and store acid forming substances and materials such as petroleum, vegetable oils, animal fats, etc.

The problem of preventing and removing cor- 'rosion from steel and other ferrous metal tanks 10 V I than ammonia gas, althoughthe process is not and containers is expensive and tedious according to present known processes. That is particularly true where the containers are adapted to receive acid forming materials, the residue of which it is desired to remove from the tank after emptying of the tank, by means of washing with salt seawater. Thus, it is conventional to remove residue materials from cargo tanks and oil tankers by washing them clean with salt sea water, by hand or mechanical means. In such cases the corrosion is violent and reaches its maximum destructive force shortly after the salt sea water has contacted the metal container. The present cheapest known method of removing residue materials from cargo tanks and oil tankers, etc. is to wash the interior of the container and then treat it with lime. For immunizing or neutralizing a sea-going oil tanker of approximately one million cubic feet internal space this conventional method of treatment would necessitate an expenditure of $75 for lime, I and in addition require approximately one hundred and twenty man hours of labor. With my improved process a tank oi. the same capacity can be emciently treated at a cost not exceeding $2.

My improved process consists in releasing from one-third of an ounce to one ounce of ammonia gas (N'Hs), or from one ounce to three ounces of ammonium hydroxide (NHiOH) in the 40 container, the metal of which is to be treated, for each one thousand cubic feet of enclosed tank space. This application must be made immediately after complete discharge of the liquid cargo in bulk, or upon discharge of ballast, or

immediately after washing the residue from the tank or compartment. This application will neutralize acids over the entire internal surface of the tank or compartment in a few minutes. Unlike conventional processes, mechanical or manual application is not necessary, since the inherent nature of the materials used produce their own locomotion and application. That is, the ammonia gas in the damp compartment, since it has an affinity for water, will penetrate and impregnate the scale and pores of the metal of the tank within a few minutes and completely neutralize all acids from forming. The scale and porous metal of the container will retain the ammonia gases indeflnite1y.- I 1 The composition does not.require,-"in order to be effective, the addition of any other chemicals than those specified, nor is heat treatment necessary in order to render the process efiective.

I'prefer to use ammonium hydroxide rather restricted to the former. That is true because commercially ammonium hydroxide is the more feasible. I

The limitations and proportions of the materials specified are important and critical, within the ranges given, because the use of smaller quantities would be insufficient to render the process effective in neutralizing acids, and the use of larger quantities would enhance an alkali corrosion, which would be even more destruc-' tive than an acid corrosion.

I am well aware that heretofore it has been proposed to apply corrosion resistant coatings to iron and steel by treating them with complicated purpose of preventing corrosion, particularly in the mode herein specified.

Various changes in the ingredients, the proportions specified, and in the steps of the process herein outlined may be made to the invention herein designated without departing from the spirit of the invention or scope of the claims.

I claim:

l. The process of treating the interior of tanks and other containers normally adapted to receive acid forming substances, for the purpose of neutralizin'g the acids and rendering the metal of the tank resistant to the action of rust promoting agents, which consist in freely releasing into the interior of the tank ammonium hydroxide in quantity sufiicient to permit the ammonia gas "therein to permeate and impregnate any scale present and the pores of the metal for preventing and neutralizing acid formations.

eration treating the compartment within the tank with an ammonia gas freely released the interior of metal tanks normally adapted to receive acid forming materials such as petroleum I products; vegetable oils, animal fats, etc., which consist in freely releasing ammonia gas into the compartment of the tank immediately after removal of the acid forming material in amount necessary to prevent the corrosion.

4. The process of preventing the corrosion of the interior of metal tanks normally adapted to receiveacid'forming materials such as petroleum products, vegetable oils, animal fats, etc., which consist in freely releasing ammonia gas into the compartmentof the tank immediately after removal of the acidforming material, in the proportions of from one third of an ounce to one ounce of the ammonia ga to each one thousand cubic feet of treated enclosed tank space.

5. The process of rendering the internal compartment walls of metal tanks (suchas cargo emptying the cargo load from the compartment 'of the tank, thereafter washing the interior of the tank, and immediately after the washing optanks) resistant to corrosion, which consists in therein.

6. The process of rendering the internalcompartment walls of metal tanks (such as cargo tanks) resistant to corrosion, which consists in emptying the cargo load from the compartment of the tank,thereafterwashing the interior of .the tank, and immediately after the washing operation releasin ammonium hydroxide into the compartment within the tank.

7. The process of rendering the internal compartment walls of metal tanks (such as cargo tanks) resistant to corrosion. whichconsists in emptying the'cargo load from the compartment of the tank, thereafter washing the interior of the tank, and immediately after the washing operation freely releasing into the compartment within the tank an ammonia gas in the proportions of from one-third of an ounce to one ounce to each one thousand cubic feet of enclosed compartment space."

8. The process of rendering the internal compartment walls of metal tanks (such as cargo tanks) resistant to corrosion, which consists in emptying the cargo load from the compartment of the tank, thereafter washing the interior of the tank, and immediately after the washing operation releasing into the compartment within the tank ammonium hydroxide in the proportion of from one ounce to three ounces of ammonium hydroxide to each one thousand cubic feet of the enclosed compartment space. I

a, Y PE'IER' HEIDT. 

